After the study of many more photos, I have revised my opinion on this question. It still remains an opinion, not a fact.
I suspect that most, if not all, were fully lined out during the Robinson period. However during World War I the lining was left off. Of course this would only apply to locos as they were shopped, they would not go in just to have the lining painted out.
If anyone has more certain information (or even a different opinion based on the evidence) I'd be very glad to hear it.